Treating lesions within the prostate is a difficult task due to the organ's complex anatomy. Due to the fact that the prostate is surrounded by important organs, such as nerve bundles and the rectum, as well as is crossed by the urethra, extreme precision is required in treating any lesion within the prostate, if collateral damages are to be avoided.
At present, brachytherapy and cryoablation, for example, are used as percutaneous techniques for treating prostate lesions. Percutaneous techniques have the advantage of minimizing surgical intervention, allowing a reduced recovery time for the patient.
Brachytherapy uses a multitude of radio-active seeds that are implanted and which destroy the tissue over a long time period (some months). Implanting the radioactive seeds is performed through the insertion of needles which are prone to deviation when inserted through tissue. Operator's skill is therefore required to minimize deviation and the locations of implant are generally monitored with an ultrasound imaging probe. The area of destruction depends on the seeds' intensity of radioactivity, which makes it possible to estimate (using a complex calculation software) the area that will be destroyed. As many seeds are implanted so as to ensure that the entire prostate gland is destroyed. However, the radio-active seeds can move over time within the tissue, resulting in a high rate of collateral damage (mainly impotence). Therefore, brachytherapy has a poor accuracy when it comes to delimiting the region to be destroyed. In addition, as radioactive seeds destroy tissue within months, brachytherapy is not well suitable for localized (or focal) destruction, because of the risk of cancer dissemination during insertion of the probes.
In cryoablation, a cryogenic fluid (most often an Argon source) is used to destroy tissue by freezing. A number of probes are percutaneously inserted in the prostate. The probes are connected to a cryogenic fluid (argon) generator, which, once activated, cools down the probes and the surrounding tissue to destroy it. The destruction effect starts from the probe and expands, forming a kind of expanding ice ball. The ice ball continues to expand even after the generator is turned off. It is therefore extremely difficult to control exactly the area of destruction. Moreover, at the boundary of the ice ball, the freezing can be reversible (the cells are not totally destroyed). An ultrasound imaging device may be used to monitor the location of the cryogenic probes, but doesn't allow monitoring the area that is destroyed. Also with this technique, the collateral damage rates (mainly impotence and rectal dysfunction) are very high.
There exists hence a need in the art to provide an alternative percutaneous technique for treating prostate lesions and which is more precise, and reduces the occurrence of collateral damage, mainly impotence and incontinence.
It is therefore an object of the present invention to provide a method of percutaneous treatment of prostate lesions, which is capable of not only precisely delimit the region that is destroyed, but also which allows to precisely predict beforehand—before imparting any damage to tissue—the region or area that will be destroyed. It is another object of the present invention to provide a method of percutaneous treatment of prostate lesions, enabling to easily and directly verify—before starting with the actual treatment—the correspondence between the volume/region that is destroyed and the volume/region that one plans to destroy.